Workpiece supporting device

ABSTRACT

A workpiece supporting device comprises a holding shaft carrying at its one end a center adapted to support one end of a workpiece. A holding force is applied against the workpiece by a spring interposed between first and second coaxial sleeves, the first sleeve being operably connected to the other end of the holding shaft through a swing arm. The holding force applied on the workpiece may be varied by adjusting the spring force, which is effected by moving the second sleeve axially. A pointer and a dial scale are connected to the first and second sleeves by rack and pinion mechanisms, respectively, for indicating the positions thereof and accordingly the holding force being applied to the workpiece.

UNITED STATES PATENTS Lunzer ..82/3l X O Unlted States Patent 1 1 6Okada [451 Apr. 4, 1972 [541 WORKPIECE SUPPORTING DEVICE 1,921,5028/1933 Brill ..s2/31 [72] Inventor: Takahim okada, Aichi, Japan1,744,780 1/1930 Mathewson ..82/31 [73] Assignee: Toyoda Koki KabushikiKaisha, Aichi- Primary Examiner-Leonidas Vlachos ken, JapanAtt0rneyOlon, Fisher & Spivak [22] Filed: Oct. 23, 1970 [57] ABSTRACT[21] Appl' 83308 A workpiece supporting device comprises a holding shaftcar rying at its one end a center adapted to support one end of a [30]Foreign Application Priority Data workpiece. A holding force is appliedagainst the workpiece by a spring interposed between first and secondcoaxial Oct. 24, 1969 Japan ..44/101562 sleeves, the first sleeve beingoperably connected to the other end of the holding shaft through a swingarm. The holding force applied on the workpiece may be varied byadjusting the [58] d 82/31 spring force, which is effected by moving thesecond sleeve ax- 1e rc iany A pointer and a dial Scale are connected tothe first and I 56] Referenm cited second sleeves by rack and pinionmechanisms, respectively,

for indicating the positions thereof and accordingly the holding forcebeing applied to the workpiece.

4 Claims, 6 Drawing Figures 27 r-- f y X X WWW; Z w 1 m N W 25* lm 1 i26 22 2/ 20a. Z0 23 l? /3 /2 PATENTED PR 4 I912 SHEET 1 [IF 3 INVENTORTAKAHIKO OKADA ATTORNEYS PATENTEDA PR 419 SHEET 2 BF 3 Fig. 4

20 20a 22 m 19 K ii x Fig.3

PATENTEUAPRY 4 I972 SHEET 3 OF 3 a hN N WORKPIECE SUPPORTING DEVICEBACKGROUND OF THE INVENTION The invention generally relates to workpiecesupporting devices, and more particularly to a tailstock wherein theholding force being applied to a workpiece by a tailstock center iseasily determined by an operator by observing a dial indicator thereon.

An excessive holding force applied on the workpiece by the tailstockcenter may cause seizure between the center hole of the workpiece andthe tailstock center or even may flex the workpiece, thus degrading theworking accuracy thereof. In the case of a deficient holding force,vibration results between the center hole of the workpiece and the tailstock center. Therefore, the holding force must be varied in accordancewith the weight or rigidity of the workpiece in order to increase theworking accuracy of the workpiece.

The holding force applied on the workpiece is conventionally provided bya compression spring and is selectively varied by adjusting the springforce until the desired holding force, as indicated by a dial indicator,is obtained. In conventional supporting devices wherein the holdingforce is indicated by the dial indicator, however, the pointer of thedial indicator usually is positioned in different angular positions,such as upwardly and downwardly directed positions, in accordance withthe adjustment of the holding force, thereby creating some difficulty inaccurately reading the scale.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide a workpiece supporting device having an easilyreadable dial indicator for indicating the holding force being appliedon a workpiece.

Another object of the present invention is to provide a workpiecesupporting device having a dial indicator for indicating the holdingforce being applied on a workpiece, wherein the dial scale of the dialindicator is rotated in accordance with an adjustment being made of theholding force along with the pointer of the dial indicator in arelatively narrow angular range.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and attendantadvantages of the present invention will be more fully appreciated asthe same becomes better understood from the following detaileddescription when considered in connection with the accompanyingdrawings, in which like reference numerals designate like orcorresponding parts throughout the several views, and wherein:

FIG. 1 is a sectional plan view showing a preferred embodiment of aworkpiece supporting device constructed according to the presentinvention;

FIG. 2 is a sectional side view taken along the line Il-II of FIG. 1;

FIG. 3 is a partial sectional view taken along the line lII-III of FIG.2;

FIG. 4 is a partial sectional view taken along the line IVIV of FIG. 1;

FIG. 5 is a partial front view, partly in section, taken along the lineV--V ofFIG. 2; and

FIG. 6 is a partial front view taken in a direction indicated by thearrow VI of FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT thereof. A push shaft 5supporting a feed shaft 7 in an axial bore therein is slidably receivedin a casing 6 secured to the housing 1. The feed shaft 7 has anexternally threaded portion 8 which engages an internally threadedsleeve 20 fixedly received in the inner end of hollow shaft 2 oppositethe tailstock center-carrying end thereof. The end wall of shaft 5 isclamped between a flange 38 formed on shaft 7 and a hand wheel 9 securedto the end of shaft 7 positioned outside the housing 1.

A radial opening 17 is provided in the peripheral wall of the push shaft5 for receiving a spherical head 16 secured to one end of a swinging, orpivotable, arm 15. Thus, the push shaft 5 is prevented from rotating,and rotation of the hand wheel 9 causes the holding shaft 2 togetherwith center 10 supported therein to move in an axial path through thethreaded engagement of threaded portion 8 of the push shaft-supportedfeed shaft 7 and the sleeve 2a. Moreover, rotation of the pivotal arm15, as described hereinbelow, causes axial movement of the push shaft 5,and of the holding arm 2 and tailstock center 10 as well, which areindirectly connected thereto through the shaft 7 and sleeve 2a.

As shown in Figure 2, the swinging arm 15 is integrally formed with anelongate transverse sleeve 30 which is rotatably received on a verticalshaft 14 mounted in the casing 6. Thus, the swinging arm 15 may beswung, or pivoted, about the shaft 14.

Another operating arm 31 is integrally formed on the lower end of thesleeve 30 on the same side as the spherical head 16 relative to theshaft 14. This operating arm 31 has an abutment 40 on one end which isadapted to engage a piston rod 33 disposed in a cylinder 32, as shown inFIG. 3. When a pressurized fluid is introduced into the cylinder 32through a radial passage 41, the piston rod 33 is caused to be movedtherein against the abutment 40 of the operating arm 31 to rotate thesleeve 30 and the swinging arm 15 integrally formed thereon in aclockwise direction, as viewed in FIG. 1. The clockwise rotation of arm15 causes rightward movement of push shaft 5 to the full extentpermitted, and accordingly of the tailstock center 10 also, which isindirectly connected thereto, to enable the workpiece 37 to be initiallylocated in a supporting position.

In the housing 1 there is fixedly received in parallel relationship withthe holding shaft 2 a bushing member 19 having a through bore thereinfor slidably receiving a sleeve 20. An end cap 21 is bolted to a flange19a integrally formed on the bushing member 19 to limit movement of thesleeve 20 in the leftward direction, as viewed in FIG. An adjusting bolt22 is threaded into the end cap 21 and contacts a closed end of sleeve20 to permit adjusting the position of sleeve 20 axially within thebushing member bore.

Another sleeve 11, being closed at one end, is also slidably received inthe housing 1 in co-axial relation with the sleeve 20. A key member 13threaded in the housing 1 is fitted into a key way, or longitudinalslot, 12 formed in the sleeve 11 to permit axial movement of the sleeve11, while preventing the same from rotating. A compression spring 23 isdisposed within the sleeves l1 and 20 between the closed ends thereof tocontinuously urge them in opposite directions. The closed end of thesleeve 11 engages an abutment 18 secured to the swinging arm 15 at aposition diametrically opposite of the spherical head 16 with respect tothe supporting shaft 14. The sleeve 11 also has a rack member 39 securedthereto and extending axially from the closed end thereof, as best shownin FIGS. 1 and 2, whereby the rotation of the swinging arm 15 alsocauses axial movement of the sleeve 11 and the rack member 39, as wellas of the push shaft 5.

Referring now to FIG. 4, the sleeve 20 is shown being provided with anannular groove 20a in the outer periphery thereof for supporting amember 29a in press-fit relation. The member 29a is received in an axialslot 1% formed in the bushing member 19 and carries an elongate, axiallyextending rack member 29 which is movably disposed in the housing 1.When the sleeve 20 is moved to the right by adjustment of the adjustingbolt 22 to increase the force of spring 23 and thereby to increase theholding force of the tailstock center 10 being applied on the workpiece37, the rack member 29 is also moved to the right.

As shown in FIGS. 2 and 5, a bracket 26 is secured to the casing 6, andslidably supports a hollow sleeve 34 at one projecting end, and a shaft35 at another spaced projecting end, the shaft 35 also being slidablyreceived within the sleeve 34. The sleeve 34 carries at one end acircular dial scale 24 and at its other end a gear 28 whichoperativelylmeshes with the rack member 29. The shaft 35 carries apointer 25 at the end thereof juxtapositioned with the dial scale 24,and at its other end a gear 27 in mesh with the rack member 39.Therefore, the dial scale 24 is rotated in accordance with axialmovement of the sleeve 20, while the pointer 25 is rotated in accordancewith axial movement of the sleeve 1 1.

In operation, when the workpiece 37 is not located in its supportingposition, the cylinder 32 is not supplied with the pressurized fluid.Thus, the outer end face of sleeve 20 is engaged with the inner end faceof the end cap 21 and the swinging arm 15 is swung counterclockwise, asobserved in FIG. 1, by the force of spring 23, operating through theclosed end wall of sleeve 11 and the abutment 18 on the swinging arm, to

cause the inner end face of shaft 5 to engage the shoulder 6a of easing6, whereby the tailstock center is in its forward end position. At thistime, the pointer 25 is positioned at 25a,

shown in dotted line fashion in FIG. 6, to indicate the minimum value ofthe holding force being applied by the tailstock center 10. Thereafter,when the cylinder 32 is supplied with pressurized fluid, the piston rod33 moves the operating arm 31 to rotate the sleeve and the swinging arm15 integrally formed thereon clockwise to move the push shaft 5 to theright. The tailstock center 10 is thus retracted by the feed shaft 7 andthe holding shaft 2 as the same are moved with the push shaft 5 untilthe center 10 occupies the extremely rightward position capable ofsupporting the workpiece 37.

The clockwise rotation of swinging arm 15 also causes leftward movementof sleeve 11 together with the rack member 39. The leftward movement ofrack member 39, as viewed in FIG. 1, causes, in turn, counterclockwiserotation of pointer 25 to the position shown at 25b in FIG. 6,, toindicate that the tailstock center 10 is fully retracted.

When the workpiece 37 is located in its supporting position and isfitted into a headstock center not shown, the cylinder 32 may beexhausted of the pressurized fluid. This causes the swinging-arm 15 toberotated counterclockwise by the force of spring 23 to move the pushshaft 5, feed shaft 7, holding shaft 2 and the tailstock center 10 tothe left as a unit to engage and support the workpiece 37, as shown inFIG. 1, applying the necessary holding force thereon. In this case, thetailstock center 10 is prevented from being further moved to the left byits engagement with the workpiece 37, with the result that there is aclearance between the inner end face of shaft 5 and the shoulder 6a ofcasing 6. At this time, the pointer 25 is positioned as shown by thesolid line form in FIG. 6, indicating that a relatively small holdingforce is being applied to the workpiece 37.

Under normal conditions, the holding force on the workpiece must-befurther increased, although there is no problem in the event that therelatively small holding force described above is available for workingoperations. The sleeve 20 is therefore moved to the right by adjustmentof adjusting bolt 22 to further compress the spring 23. Upon furthercompression of spring 23, the holding force on the workpiece isincreased by means of the swinging arm 15, shafts 5, 7 and 2,

- and the tailstock center 10. At the same time, rightward movement ofthe sleeve 20 causes clockwise rotation of gear 28 together with dialscale 24, as viewed in FIGS. 5 and 6, by

means of rack member 29, so that the pointer. 25 indicates a relativelylarge value on the dial scale 24, corresponding to the relativelygreater holding force being applied on the workpiece 37. Therefore, theoperator can adjust the adjusting bolt 22, while observing the valueindicated bgcpointer 25 on the dial scale 24, so that the workpiece maysupported by the tailstock center with a predetermined optimum holdingforce.

In this embodiment, when the tailstock center 10 is not fully engagedwith the workpiece 37, and when the sleeve 20 occupies a positionwherein it is spaced apart from the inner face of end cap 21 because ofan adjustment of the bolt 22 has been made, and the inner end face ofpush shaft 5 engages the shoulder 6a of casing 6, the pointer 25 ispositioned at 25a as shown in FIG. 6. That full engagement has not beenmade is thus readily apparent, since this position of the pointer 25indicates normally that no workpiece is located between the headstockand tailstock, or that an applying force of minimum value is beingapplied to a workpiece. Therefore, an index mark 42 is set out on casing6 at a position corresponding to the position 25a of pointer 25, wherebythe operator can easily inspect whether or not the tailstock center 10is in full engagement with the workpiece 37. Rotation of the hand wheel9.then permits the push shaft 5 to be moved back away from the shoulder6a of casing 6 to bring the tailstock center 10 into full engagementwith the workpiece 37 While the invention has been described by means ofthe specific embodiment, it should be understood that the novelcharacteristics of the invention may be incorporated in the otherstructural forms without-departing from the spirit and scope of theinvention. Accordingly, it is to be understood that within the scope oftheappended claims, the invention may be practiced otherwise than asspecifically described herein.

What is claimed as new and desired to be secured by letters patent ofthe United States is:

1. In a device for supporting a workpiece including a housing, a holdingshaft slidably but non-rotatably received in said housing, a centercarried on one end of said holding shaft and adapted to support one endof said workpiece and means for adjusting an axial position of saidholding shaft by threaded engagement therewith, the improvementcomprising:

a swinging member rotatably supported on a shaft member mounted in saidhousing and being connected at one end thereof to said adjusting means;

first and second coaxially disposed sleeve members slidably received insaid housing in parallel relationship with said holding shaft;

resilient means interposed between said first and second sleeve membersfor normally urging said sleeve members said first sleeve member beingengaged with the other en of said swinging member for applying aholdingforce through said swinging member, said adjusting means and saidholding shaft to said workpiece;

means for adjusting the axial position of said second sleeve member tovary the holding force applied on said workpiece;

a rotatable pointer operably connected to said first sleeve member to berotated by axial movement thereof; and

a rotatable dial scale associated with said pointer and operablyconnected to said second sleeve member tobe rotated by axial movementthereof caused by said adjusting means for said second sleeve member.

2. A workpiece supporting device as set forth in claim 1, wherein saidpointer and said dial scale are connected to said first and secondsleeve members by rack and pinion mechanisms, respectively.

3. A workpiece supporting device as set forth in claim 1, furthercomprising fluid actuated means for rotating said swinging memberagainst said resilient means to retract said center from said workpiece.

4. A workpiece supporting device as set forth in claim 1, I

1. In a device for supporting a workpiece including a housing, a holdingshaft slidably but non-rotatably received in said housing, a centercarried on one end of said holding shaft and adapted to support one endof said workpiece and means for adjusting an axial position of saidholding shaft by threaded engagement therewith, the improvementcomprising: a swinging member rotatably supported on a shaft membermounted in said housing and being connected at one end thereof to saidadjusting means; first and second coaxially disposed sleeve membersslidably received in said housing in parallel relationship with saidholding shaft; resilient means interposed between said first and secondsleeve members for normally urging said sleeve members apart; said firstsleeve member being engaged with the other end of said swinging memberfor applying a holding force through said swinging member, saidadjusting means and said holDing shaft to said workpiece; means foradjusting the axial position of said second sleeve member to vary theholding force applied on said workpiece; a rotatable pointer operablyconnected to said first sleeve member to be rotated by axial movementthereof; and a rotatable dial scale associated with said pointer andoperably connected to said second sleeve member to be rotated by axialmovement thereof caused by said adjusting means for said second sleevemember.
 2. A workpiece supporting device as set forth in claim 1,wherein said pointer and said dial scale are connected to said first andsecond sleeve members by rack and pinion mechanisms, respectively.
 3. Aworkpiece supporting device as set forth in claim 1, further comprisingfluid actuated means for rotating said swinging member against saidresilient means to retract said center from said workpiece.
 4. Aworkpiece supporting device as set forth in claim 1, further comprisingan index mark on said housing juxtapositioned with said dial scale forindicating the applying force of minimum value regardless of the angularposition of said dial scale when said pointer is directed to said indexmark.